fan off for dark period - tempsi

I'm running autos so my dark period is short - just 3 hours - but n that short time with the lights out the temps were dropping like 25 degrees (f) ...last couple days I've had the fan shut off with the lights so the temp difference is now down to about 12f ...just wondering if it's bad to stop air exchange for tht long? The girls seem to be liking it so far but they aren't very big yet. Gonna have to figure something out for when I start running photos n have a 12 hr dark period :/

i don't c a problem in veg but humidity will be high in flower when lights off...not a good thing

brimck325 said:

i don't c a problem in veg but humidity will be high in flower when lights off...not a good thing

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Prob better to have cooler temps n dryer humidity during flower tho right? So leaving the fan on during the dark period when they start flowering would be a good idea? I just thought the big swing in temps was too much for the young (1.5 week old) plants. They look relatively healthy - just growing a little on the slow side

As long as your ambient temp is within comfortable parameters your origional temp difference of 25f (10c ish) is within the sweet zone. fans off will effect humidity. this will affect your plant either negatively, or positively depending on your climate/air the plant sits in

reddan1981 said:

As long as your ambient temp is within comfortable parameters your origional temp difference of 25f (10c ish) is within the sweet zone. fans off will effect humidity. this will affect your plant either negatively, or positively depending on your climate/air the plant sits in

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The humidity stays below 30% with the fan and lights on - goes up a bit during the dark period, but never been over 45% so far (lights on or off, fan on or off). I'm still new to this so having a hard time figuring out what's actually 'ideal' conditions. I've seen a lot of conflicting info on the topic

keep your plants within temps you yourself will be comfortable in. If they get cold give them a radiator. Ive got a green house rad its a small tube set to 18c keeps my tent comfortable when outside temps get chilly its cheap and gives me peace of mind

throughout their life from start to finish plants can cope with extremes of humidity swings most will prefer slightly more humid conditions of around 60 percent throughout. However to reduce risks of mould during flower, growers generally lower humidity which can also create a response to increase resin from the plant

I would consider 30-45% humidity as relatively low. Mine gets up to 60% at times with no noticeable problems.

Balvtr said:

I would consider 30-45% humidity as relatively low. Mine gets up to 60% at times with no noticeable problems.

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The weird thing is it's in a basement that's got relatively high humidity - the tent just seems to stay real low RH inside. I guess running the fan and light all day is causing it, n 3 hours isn't long enough to bring it back up

ayr0n said:

The weird thing is it's in a basement that's got relatively high humidity - the tent just seems to stay real low RH inside. I guess running the fan and light all day is causing it, n 3 hours isn't long enough to bring it back up

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Your logic seems sounds. For me, I try to keep vegging RH around 50-60% and flowering more around 45-50%. Better for it to be lower RH than too high, imo.